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On Tue, 20 Jan 2015 10:40:17 +0100 |
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Michał Górny <mgorny@g.o> wrote: |
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> # Copyright 1999-2014 Gentoo Foundation. |
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> # Distributed under the terms of the GNU General Public License v2 |
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> # $Header$ |
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> |
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> # Whenever the flag name does not correspond to /proc/cpuinfo flags, |
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> # please put the cpuinfo flag in square brackets. If more than one |
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> flag # is specified, any of them will enable the respective USE flag. |
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> |
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nice |
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now, letmegrepitforyou: |
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> avx - Adds support for Advanced Vector Extensions instructions |
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media-video/ffmpeg:avx - Adds support for Advanced Vector Extensions |
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instructions (Intel Sandy Bridge, AMD Bulldozer and later chips) |
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> avx2 - Adds support for Advanced Vector Extensions 2 instructions |
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media-video/ffmpeg:avx2 - Adds support for Advanced Vector Extensions 2 |
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instructions (Intel Haswell and later chips) |
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> fma3 - Use the Fused Multiply Add 3 instruction set ([fma] in cpuinfo) |
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media-video/ffmpeg:fma3 - Enables FMA3 optimizations: AMD processors |
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starting with Piledriver architecture and Intel Haswell based |
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processors or later. |
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> fma4 - Use the Fused Multiply Add 4 instruction set |
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media-video/ffmpeg:fma4 - Enables FMA4 optimizations: AMD processors |
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starting with Bulldozer architecture. |
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> sse4_1 - Enable SSE4.1 instruction support |
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media-libs/libvpx:sse4_1 - Enable optimization for SSE4_1 capable |
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processors (Intel Core 2 Penryn and later chips) |
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> sse4_2 - Enable SSE4.2 instruction support |
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media-video/ffmpeg:sse4_2 - Enables SSE4.2 optimizations: Nehalem-based |
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Intel Core i7 or later. |
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> ssse3 - Use the SSSE3 instruction set (NOT sse3/pni) |
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media-libs/libvpx:ssse3 - faster floating point optimization for SSSE3 |
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capable chips (Intel Core 2 and later chips) |
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I like the "available in cpu $foo and later" because this influences me |
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in what to buy: If I know that I will have noticeable gain with hand |
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written asm in a package that is critical to me, I know it will perform |
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better for my needs despite benchmarks might be saying otherwise. |
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Alexis. |
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